Hydrotechnik

Pressure sensors primarily convert system pressure values into electrical signals and transmit them to the relevant system. Aside from connection characteristics, the two most important features when describing pressure sensors are the measuring pressure range and output signal type. Measuring Pressure Ranges: (-1, +6 Bar), (0-1 Bar), (0-10 Bar), (0-25 Bar), (0-60 Bar), (0-100 Bar), (0-250 Bar), (0-400 Bar), (0-600 Bar), (0-1000 Bar) Regarding the measuring output signal, the device typically generates an analog signal. This signal can be a current or voltage output that changes according to the received pressure. The most preferred types are 0-10V and 4-20mA, but other output signals, such as (0-20mA), (1-5V), (2-10V), (0.5-4.5V), and (±10V), are also used.

Resistance thermometers are the most commonly used sensors in industry and laboratories, particularly for troubleshooting applications. These sensors measure temperature by interpreting the change in resistance of a conductive wire, typically platinum or nickel wires known as Pt100. Pt100 sensors output in ohms, reading the varying resistances of the two wires placed within a metal sheath. The most preferred measuring pressure range is -50 to +200 °C. For the output signal, ohm or 4-20mA are the most popular choices.

Flow sensors convert the flow value on the line where they are mounted into electrical signals and transmit them to the appropriate system. Working principle types include: • Turbine type • Gear type • Electromagnetic • Ultrasonic • Float • Thermal Mass • Vortex • Venturi and more.

Gear flow meters have a measurement accuracy between 0.1% and 0.5%, making them more popular in test and R&D systems. Viscosity ranges span from 5-120,000 cSt, and working pressures range between 350 and 630 Bar.

Speed sensors measure the revolutions of electric and hydro motors driving the pumps in hydraulic systems. Measurements can be taken from mechanical bodies with magnetic sensors and reflective and non-reflective sensors that measure with light.

Position sensors, also known as linear rulers, are linear position-reading sensors mounted on mechanical parts or placed in hydraulic cylinders to provide instant position information for the automation system to act accordingly. Analog output signals include 4-20 mA or 0-10V.

Torque sensors in hydraulic systems are mounted between electric motors and pumps or between hydro motors and the mechanisms they drive. Rated values include rated torque range, maximum speed, mass moment of inertia (driving side and measuring side), lateral forces, and output signal.

Sensors for pollution value reporting provide data in several ways: • Own Memory: These sensors store up to 250 test data points, which you can access and report using a program. • Online Measurements: By working with a computer program, these sensors send real-time results and accumulated test data to the computer for reporting. • Analog Output: The sensors give a 4-20 mA output signal in a specific sequence for four distinct measurements within a set time period, allowing integration with the current electronic system to access the values. • Switch Output: Based on the requirements of the system in use, a switch gets incorporated into the measurement sensor. The pollution level gets recorded, and a contact signal gets sent externally when the measurement reaches this level. • RS232 or CanBus Signal: Use this output signal to connect to the measuring device or SCADA system, enabling continuous data transmission.

Oil analysis sensors measure and report particulate pollution, moisture content, dielectric coefficient, viscosity, metal pollution, and hydraulic oil temperatures. The oil flow first enters the particle sensor, passes through a pressure reducer (for high pressure), and then reaches the humidity and viscosity sensors. Optionally, you can add a metal contamination sensor to the system. If preferred, you can use these sensor outputs individually in measurement systems or collect and analyze the data via Can Bus in a measuring device. The goal is to maintain complete control to prevent oil-related issues. These sensors ensure continuous analysis across different hydraulic systems within an organization. By comparing measurements taken at specific intervals with previous results, the system aims to prevent malfunctions by determining oil life and aging time and identifying the types of pollutants present.

Current and voltage sensors collect control signals applied to proportional and servo valves in hydraulic systems. When testing proportional or servo systems, these sensors enable data collection of the signal applied to the proportional valve, along with values read by the pressure sensor and flowmeter connected to the system. This data can then be examined on the same graph.

Developed by "Hydrotechnik" in the 1950s, Minimess® connection unions are special fittings that offer safe and leak-free connections to high-pressure lines. Machinery and hydraulic power unit manufacturers incorporate these unions at critical points and on blocks during system design, ensuring accessible intervention for long-term maintenance, analysis, and short-term commissioning without stopping the system. A well-designed hydraulic power unit cannot be imagined without Minimess®. The internal structure of Minimess® unions consists of male threaded fittings on both sides and a hexagonal key holding area in the middle, as illustrated below. A chain cover has been developed to protect the interface from dust and other contaminants when Minimess® is not in use.

Minimess® couplings come in various types, with the most widely used being those with an M16x2 (covered part) connection interface, providing DN2 diameter permeability. Other Minimess® glands include M12x1.5, M16x1.5, and M16x4 connection interfaces. In the block connection section, options are vast. The most commonly used type is the 1/4" BSP male threaded product. BSP thread options include 1/8", 3/8", and 1/2" products. Additionally, threaded products in Metric, UNF, NPT, and JIC standards are available. Minimess® unions, categorized into four types based on their connection interfaces, are primarily developed for different applications: • M16x2 products are used in hydraulic lines, standard industrial, and mobile systems. • M12x1.5 products, with their compact structure, are suitable for industrial and mobile systems in confined spaces. • M16x1.5 military products are designed for hydraulic lines and gas lines. • M16x4 DN4 diameter products are used in hydraulic lines and locations that require flow. Minimess® couplings also have products developed for connecting to the installation, besides male thread connections in block connection parts. Various types are shown in the accompanying photos.

In all types of mobile and industrial hydraulic applications, such as during operation or testing of pumps, valves, working elements, cylinders, and hydro-motors, measurements are taken to control, observe, and record various variables like pressure, temperature, flow rate, and pollution levels. These measurements can then be recorded and reported as graphs or tables. If needed, measurements can be taken at microsecond intervals.